This is what I think about the x-step. When you are trying to throw an object, it is natural to try to create an initial velocity by moving yourself in the direction you want to throw. It is what we do when we throw just about any object. The disc golf throw is different. In order to maximize power, your feet/knees/hips/shoulders/elbow/wrist/(grip point) need to all work together in nearly perfect timing. Each piece compounds the acceleration given to the disc.
So the x-step is mainly used to get the feet in correct position to maximize with weight shift at release. It is also helpful to use it for timing the rest of your throw.
I think that if a person is able to maintain the timing of their throw with a larger x-step, this will make the weight shift cover more ground and impart more initial velocity to the system. The faster your body is moving, the less time you have to perform the throw with your feet planted correctly. I think this also narrows the already tight timing window that needs to be hit for the best snap.
So in conclusion, the more aggressive the x-step, the more distance is covered, the more initial velocity is added, the quicker the throw needs to be, the smaller the timing window is made, and the more power/distance your throw will have.
